In the oxygen production of steel, typically by the basic oxygen process, scrap metal and molten iron are charged into a generally cylindrical refractory-line converter at the upper end of which is provided a mouth opening surrounded by an annular lip ring. The charge is subject to a high velocity blow of relatively pure oxygen that is delivered to the charge through an oxygen lance that extends into the converter through the mouth opening. The oxygen blow, besides refining the converter charge, also produces a considerable amount of turbulance therein causing considerable splattering. As a result of this splattering, molten metal and other debris, commonly referred to as skull, are deposited on the converter lip ring. Since skull forms an obstruction that gradually closes the mouth opening, continued operation of the converter requires that skull be removed when it reaches an objectionable level.
The deskulling operation is conventionally conducted in one of the following ways: by repeated oscillation of the converter past a plurality of steel billets that protrude into the path of the skull thereby raking the same from the surface of the lip ring; by dislodging the skull by means of hydraulic or pneumatic jack hammers; or by battering the lip ring with a deskulling ram that is normally suspended from and operated by an overhead crane. Each of these methods of removing skull will, after repeated applications, ultimately result in damage to the converter, typically to the lip ring or to the converter shell adjacent thereto. Alternatively however, the damage may be to the refractory lining that underlies the upper region of the converter top cone. In either event, the affected portion of the unit must be replaced. In the past, when the lip ring was directly attached to the top cone of the converter, it was necessary to replace the entire top cone even though damage was limited to that region of the top cone underlying the lip ring. Such replacement of the entire top cone is undesirable for several reasons. It requires the laborious efforts of a team of workmen, usually upwards of 10, to manipulate pry bars, cables, and a heavy counterweight removal device for an extended period of time. It further presents a safety problem in that the working apparatus, such as torch hoses, welding leads and cables offer a definite tripping hazard to the workmen. Moreover, because an overhead crane is required to remove the spent top cone from the converter and to install the new one thereon, its availability in connection with the operation of other converters in the immediate vicinity is adversely affected, thereby tending to retard and maybe even to terminate the operation of these other converters.
It has been suggested to form the lip ring of a steelmaking converter as a member detachable from the top cone portion of the shell. U.S. Pat. No. 3,350,085, issued Oct. 31, 1967 to R. E. Over, discloses apparatus of this type. However, structures such as those described in this patent are not totally dispositive of the problem in view of the fact that the connection between the lip ring and the converter top cone is made through flanges that are disposed parallel to the direction of the shear forces to which the unit will be subject when deskulling of the lip ring is conducted. Therefore, in order to accommodate these shear forces, a great number of large diameter bolts or studs are required to secure the lip ring to the top cone. The use of such large bolts or studs in connecting these members is costly both from the standpoint of equipment requirements and also in the amount of time necessary to remove a spent lip ring and install a new one when replacement of the lip ring is required.
It is to the solution of such problems, therefore, that the present invention is directed.